16 August 2014

How to Discover a Planet from your Sofa

August is often described as the ‘Silly Season’ by those who work in the news media because politicians and others go on holiday and so not much seems to happen. Journalists are consequently obliged to write ‘silly stories’ about us ordinary mortals. As far as I’m concerned I’d be quite happy if the politicians stayed on holiday for a lot longer and let us get on with our lives. In any event noone can describe this month as “silly”; “stupid” would be more accurate with the continuing tragedies in Syria, Iraq, Gaza, the Ukraine and the Ebola outbreak in Africa. But for me the most significant event so far this month was when Rosetta, the European Space Agency (ESA) mission to intercept Comet 67P/Churymov-Geraisimenkpo, took place last week on 6th August. This mission had been thirty years in the planning and Rosetta was launched ten years ago. It had spent two-and-a half years in hibernation waiting for Comet 67P to come into range. Now the real science starts as it attempts to ‘land’ on the Comet and gather data which may yield us more of the secrets of the origin of the universe, or at least our galaxy.

By chance the previous week I had attended the Oxford University Society London Branch 11th Annual Lecture delivered by Dr Chris Lintott, researcher in Astrophysics at Oxford and a Research Fellow of New College, my alma mater. In 2003 Chris Lintott joined the BBC’s Sky at Night TV programme as astronomical researcher, then became the show’s co-presenter alongside the late Sir Patrick Moore with whom he co-wrote ‘Bang-The Complete History of the Universe’ with the additional collaboration of Brian May, the astrophysicist guitarist of rock-group Queen!

Dr Lintott introduced the concept of finding new planets in our galaxy-something he claimed was the most exciting area of science. This has been possible only in the last twenty years, largely due to the increasing accuracy of digital photography. He started his lecture by showing the latest pictures taken from Rosetta which was the first probe to fly along a comet. A comet’s gravity is one millionth that of Earth. Over the next few months Rosetta will track 67P closely spiralling in to approach within 20 miles or so of its objective. It will survey the surface and select a landing site for Philae, a landing vehicle that will be released in November and effectively harpoon the comet. A comet appears made up of dirty ice but its particles are pristine pieces of the early solar system. They are one tenth the size of grains of sand.

The search for new planets within the galaxy is now highly active. So far three Earth-like planets have been discovered for each person on Earth. Eventually this search will evolve into a search for life and, with that many similar-sized planets; it seems inevitable, indeed statistically virtually certain, that such life exists. Life needs water but also vapour water ice. For Dr Lintott this means we should look for a planet where you can have a decent gin and tonic, i.e. one with a complex chemical system. Of the 17 billion Earth-like planets to have been discovered so far a few hundred have been observed by ordinary people using their PCs at home. Galaxy Zoo[i] and its various successors have run as crowd-sourcing observations since 2006 using astrophotography from the world’s largest telescopes. In Galaxy Zoo there were over 350 million observations by 150,000 volunteers, many of whom observed new galaxies and within our galaxy new planets. A planet can be observed by watching a star and seeing a ‘blip’ in its orbit.

One such volunteer was a 71-year old living in Gateshead who helped find a new planet. When asked why he joined in the project he said:

“There’s nowt on telly and only so much gardening you can do.”

Clearly planets are common but are very diverse. One was found in a four-star system. Two pairs of stars were observed orbiting each other on a three-day orbit. Another planet was found circumnavigating an orbit of two stars and all of these were discovered by volunteers.

The key lesson of the Apollo missions was that the craters on the moon are 850 million years later than the creation of the solar system. Subsequent analysis has shown that Saturn and Jupiter have changed places in their orbit of the Sun while Neptune and Uranus have done the same. These massive movements produced chaos which led to mass bombardments of the Earth and its moon.

Dr Lintott also told us of wandering planets. There might be one in our own solar system which could be the fifth largest of the planets. There could be more of such bodies than the stars themselves. NASA will launch its Transiting Exoplanetary Survey Satellite (TESS) in 2017 to focus mainly on discovering new Earths and Super-Earths in the solar neighbourhood. While in Chile The Large Synoptic Survey Telescope (LSST) is being built which from 2022 will photograph all the available sky every three nights. Oxford University is the only European partner in this project. All data will be released for free.

Dr Lintott told us that with such investments in photography of the skies the progress of our knowledge through astronomy is only limited by the number of astronomers and these do not need to be professional scientists. If you would like to join the growing ranks of those who seek to find a planet from the comfort of their sofa go to www.zooniverse.org . More than a million volunteers have registered so far.

In 2010 The Prime Minister appointed Chris Lintott as a trustee of the National Maritime Museum and that is where the lecture was held. An astronomer has been on the board of trustees since the eighteenth century when knowledge of the skies was an essential aid to navigation. This year marks the 300th anniversary of the Longitude Act when Parliament offered a prize of £10,000 to the first person to come up with a reliable way of finding longitude while at sea. The museum has a major new exhibition entitled ‘Ships, Clocks and Stars: The Quest for Longitude’ to mark the occasion. It was a fitting venue in which to hear such an inspirational lecture.